Claude Mythos 5 vs GLM-5.1
Claude Mythos 5 (2026) and GLM-5.1 (2026) are frontier-tier reasoning models from Anthropic and Zhipu AI. Claude Mythos 5 ships a 1m-token context window, while GLM-5.1 ships a 200k-token context window. On Humanity's Last Exam, Claude Mythos 5 leads by 33.5 pts. On pricing, GLM-5.1 costs $1.05/1M input tokens versus $10/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
GLM-5.1 is ~852% cheaper at $1.05/1M; pay for Claude Mythos 5 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Mythos 5 | GLM-5.1 |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, tool-calling agents, and provider-routed production |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 200k |
| Cheapest output | $50/1M tokens | $3.50/1M tokens |
| Provider routes | 3 tracked | 5 tracked |
| Shared benchmarks | Humanity's Last Exam leader | 1 shared |
Decision tradeoffs
- Claude Mythos 5 holds a shared-benchmark lead on Humanity's Last Exam, ahead by 33.5 points.
- Claude Mythos 5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Mythos 5 uniquely exposes Vision and Multimodal in local model data.
- Local decision data tags Claude Mythos 5 for Coding, RAG, and Agents.
- GLM-5.1 has the lower cheapest tracked output price at $3.50/1M tokens.
- GLM-5.1 has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags GLM-5.1 for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Mythos 5
$20,500
Cheapest tracked route/tier: Anthropic
GLM-5.1
$1,715
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $18,785. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Claude Mythos 5 and GLM-5.1; plan for SDK, billing, or endpoint changes.
- GLM-5.1 is $46.50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision and Multimodal before moving production traffic.
- No overlapping tracked provider route is sourced for GLM-5.1 and Claude Mythos 5; plan for SDK, billing, or endpoint changes.
- Claude Mythos 5 is $46.50/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Mythos 5 adds Vision and Multimodal in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-06-09 | 2026-04-07 |
| Context window | 1m | 200k |
| Parameters | — | 754B total, 40B active |
| Architecture | Decoder Only | Mixture of Experts |
| License | Proprietary | MITOSI-approved |
| Openness | Proprietary | Open source |
| Commercial use | Commercial use: conditional | Commercial use: permitted |
| Knowledge cutoff | - | 2025-11 |
Pricing and availability
| Pricing attribute | Claude Mythos 5 | GLM-5.1 |
|---|---|---|
| Input price | $10/1M tokens | $1.05/1M tokens |
| Output price | $50/1M tokens | $3.50/1M tokens |
| Providers |
Capabilities
| Capability | Claude Mythos 5 | GLM-5.1 |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Claude Mythos 5 | GLM-5.1 |
|---|---|---|
| Humanity's Last Exam | 64.5 | 31.0 |
Deep dive
On shared benchmark coverage, Humanity's Last Exam has Claude Mythos 5 at 64.5 and GLM-5.1 at 31, with Claude Mythos 5 ahead by 33.5 points. The largest visible gap is 33.5 points on Humanity's Last Exam, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on vision: Claude Mythos 5 and multimodal input: Claude Mythos 5. Both models share reasoning mode, function calling, tool use, and structured outputs, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Claude Mythos 5 lists $10/1M input and $50/1M output tokens on the cheapest tracked provider, while GLM-5.1 lists $1.05/1M input and $3.50/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts GLM-5.1 lower by about $20.21 per million blended tokens. Availability is 3 providers versus 5, so concentration risk also matters.
Choose Claude Mythos 5 when coding workflow support and larger context windows are central to the workload. Choose GLM-5.1 when coding workflow support, lower input-token cost, and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Mythos 5 or GLM-5.1?
Claude Mythos 5 supports 1m tokens, while GLM-5.1 supports 200k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Mythos 5 or GLM-5.1?
GLM-5.1 is cheaper on tracked token pricing. Claude Mythos 5 costs $10/1M input and $50/1M output tokens. GLM-5.1 costs $1.05/1M input and $3.50/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Mythos 5 or GLM-5.1 open source?
Claude Mythos 5 is listed under Proprietary. GLM-5.1 is listed under MIT. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Mythos 5 or GLM-5.1?
Claude Mythos 5 has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Claude Mythos 5 or GLM-5.1?
Claude Mythos 5 has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Claude Mythos 5 and GLM-5.1?
Claude Mythos 5 is available on Anthropic, AWS Bedrock, and GCP Vertex AI. GLM-5.1 is available on Z.ai, OpenRouter, Fireworks AI, Vercel AI Gateway, and Novita AI. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-06-24. Data sourced from public model cards and provider documentation.